TRYPTOPHAN METABOLISM IN ALCOHOLISM. TRYPTOPHAN BUT NOT EXCITATORY AMINO ACID AVAILABILITY TO THE BRAIN IS INCREASED BEFORE THE APPEARANCE OF THE ALCOHOL-WITHDRAWAL SYNDROME IN MEN

Tryptophan (Trp) metabolism and disposition and excitatory andother amino acid concentrations were determined in alcohol-dependentsubjects in relation to the alcohol-withdrawal syndrome (AWS).Parameters were examined in 12 alcohol-dependent male subjects,undergoing elective upper digestive tract tumour resection,and 12 age-, gender-, and medication-matched controls on threeoccasions: pre-operatively, post-operatively, and immediatelybefore (i.e. within 24 h of) the appearance of the AWS. No significantdifferences were observed between controls and alcoholic subjectson the first or second of these occasions. On the third occasion,within 24 h of the appearance of the AWS, alcoholics showeda dramatic elevation (117%) in free serum Tip concentrationand a consequent increase (111%) in the ratio of [free Trp]/[competingamino acids], which is an accurate predictor of Trp entry intothe brain. Increases were also observed on this third occasionin concentrations of total Trp (49%), cortisol (123%), and norharman(137%). Concentrations of glutamate, glycine, aspartate, serine,and taurine did not differ significantly within or between thecontrol and alcohol-dependent groups of subjects on any of thethree occasions. The possible significance of the Trp and relatedmetabolic changes in relation to the behavioural features ofthe AWS is discussed.